Ferrovalley Physics in Stacked Bilayer Altermagnetic Systems

TL;DR

This paper demonstrates that interlayer sliding in stacked bilayer altermagnetic systems can induce and control large valley polarization, revealing new properties relevant for spintronics and valleytronics.

Contribution

It introduces a novel method of using interlayer sliding to manipulate valley polarization in altermagnets, supported by theoretical models and first-principles calculations.

Findings

Sliding induces ferrovalley states with unique optical properties.

Large valley polarization can be effectively controlled via interlayer sliding.

Predicted effects include optical dichroism and anomalous valley Hall effect.

Abstract

As an emerging magnetic phase, altermagnets with compensated magnetic order and non-relativistic spin-splitting have attracted widespread attention. Currently, strain engineering is considered to be an effective method for inducing valley polarization in altermagnets, however, achieving controllable switching of valley polarization is extremely challenging. Herein, combined with tight-binding model and first-principles calculations, we propose that interlayer sliding can be used to successfully induce and effectively manipulate the large valley polarization in altermagnets. Using Fe2MX4 (M = Mo, W; X = S, Se or Te) family as examples, we predict that sliding induced ferrovalley states in such systems can exhibit many unique properties, including the linearly optical dichroism that is independent of spin-orbit coupling, and the anomalous valley Hall effect. These findings imply the correlation among spin, valley, layer and optical degrees of freedom that makes altermagnets attractive in spintronics, valleytronics and even their crossing areas.